Drying with Formation of Capillary Rings in a Model Porous Medium
Drying with Formation of Capillary Rings in a Model Porous Medium
复制标题
DOI：
10.1007/s11242-015-0538-1
复制
发表时间：
2015-11-01
影响因子：
2.7
通讯作者：
Prat, M.
中科院分区：
文献类型：
--
作者：
Vorhauer, N.;Wang, Y. J.;Prat, M.
在没有可调参数的情况下对干燥过程进行建模仍然是一个挑战。正如在以前的几个工作中强调的那样，这可能部分是由于捕获在孔隙空间角落的液膜的影响。在这项研究中，我们提出并分析了一个微型模型的干燥实验，它清楚地显示了角膜层的存在。然而，与以前的工作不同的是，在我们的微观模型中，角膜并没有形成一个相互连接的角膜系统，这些角膜在大范围内延伸。相反，它们在设备的固体块周围形成孤立的毛细管环，因此，在土壤中的颗粒和颗粒堆积之间的接触区域经常可以观察到准二维版本的液桥。这些毛细管环基本上保持在两相区域内。因此，它们对干燥速度的影响比有利于远距离液压连接薄膜的系统要小得多。该模型考虑了毛细液环的形成，只要考虑了实验中观察到的液体侧向钉扎现象，就可以得到与实验相符的结果。在此基础上，该模型丰富了干燥孔网络模型家族，可被认为是在更复杂的几何形状中模拟干燥中的二次毛细效应的一步。
Modelling of drying processes without adjustable parameters is still a challenge. As emphasized in several previous works, this might partly be due to the impact of liquid films trapped in corners of the pore space. In this study, we present and analyse a drying experiment with a micromodel, which clearly shows the presence of corner films. In contrast with previous works, however, the corner films do not form a system of interconnected corner films extending over large regions in our micromodel. They rather form isolated capillary rings surrounding the solid blocks of the device, and thus, a quasi-two-dimensional version of liquid bridges often observed in the contact regions between grains in soils and packings of particles. These capillary rings essentially remain confined in the two-phase region. As a result, their impact on drying rate is much smaller than in systems favouring films hydraulically connected over long distances. The capillary liquid ring formation is taken into account in a pore network model of drying leading to satisfactory agreement with the experiment provided that the lateral pinning of liquid phase observed in the experiment is included in the model. Based on this, the model enriches the family of pore network models of drying and can be considered as a step towards the modelling of secondary capillary effects in drying in more complex geometry.